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Sampled Values Waveform & Phasor Viewer (IEC 61850-9-2LE)

Open a process-bus capture and see what the merging unit really sends: current and voltage waveforms, phasors from a one-cycle DFT, frequency and symmetrical components — with checks for lost samples, synchronisation, quality, a neutral that does not match the phases, and swapped phases.

Capture

Result

Open a process-bus capture or load the sample.

Tool guide · know before you use

What this tool is, how it works and how far to trust it

A viewer for IEC 61850-9-2 / 9-2LE sampled values in a capture: waveforms, phasors and plausibility checks.

Read this before relying on a result. Every method, formula, assumption and limit is stated here, so you can check the answer yourself instead of accepting it blindly.

What it can do

  • Decode sampled-value streams (svID, smpCnt, confRev, smpSynch, eight values and qualities).
  • Plot two cycles of currents and voltages from any sample; compute RMS phasors (one-cycle DFT), frequency and sequence components.
  • Check lost samples, synchronisation, simulation, quality, neutral against the phase sum, phase sequence, unbalance and frequency.

Why you need it

  • With a process bus, CT/VT wiring errors become channel-mapping and configuration errors that are invisible until the samples are inspected.
  • Lost or unsynchronised samples block or degrade differential and distance protection.

Understand this first

  • 9-2LE sends 80 samples per cycle (4000/s at 50 Hz) of Ia, Ib, Ic, In, Va, Vb, Vc, Vn with 1 mA and 10 mV resolution; smpCnt counts 0…3999 and wraps every second.
  • smpSynch 2 means globally synchronised (GPS/PTP); only synchronised streams from different merging units can be combined.
  • For a measured neutral, In equals Ia + Ib + Ic at every instant.

What you need before you start

  • A process-bus capture (.pcap / .pcapng) at the relay's port.
  • The nominal frequency and samples per cycle (defaults 50 Hz, 80).
  • A current browser (Chrome, Edge, Firefox or Safari). Nothing is installed and your data is never uploaded; it is processed on your own computer.

How to use it

  • Open the capture or load the sample; choose the stream.
  • Move the window to inspect waveforms; use 'Go to the lost samples' when samples are missing.
  • Read the phasors and the checks.

What you get

  • Stream data, findings, waveform plots, phasor diagrams with a table, frequency and sequence components.

How to read the results

  • Lost samples: network load, merging unit or capture problem — check before testing protection.
  • Neutral mismatch: neutral CT ratio or polarity, or the In channel mapping.
  • A-C-B sequence: two phases swapped in wiring or mapping.

Technical basis

  • UCA 9-2LE guideline and IEC 61869-9; phasor X = (√2/N) Σ x[n] e^(−j2πn/N) over one cycle; frequency from the phase advance between consecutive cycles; symmetrical components with a = 1∠120°.

Limits: when not to rely on it

  • Scaling follows 9-2LE; other IEC 61869-9 streams show proportional values.
  • One-cycle DFT phasors include harmonics leakage when the frequency deviates from nominal.

Sample files for this tool

Download, open and compare with what the guide says you should see.

All sample files and what to expect →

For preliminary engineering use. Results must be checked by a qualified engineer against the project's standards. How results are checked · Terms & disclaimer · Build 0473054 · 2026-11-14